Battery devices, such as rechargeable batteries, battery packs or terminal equipment having permanently installed chargeable battery cells are typically charged with the aid of external charging stations. This includes inter alia utilizing charging methods which use a contactless energy transmission between the charging station and the battery device. In an inductive charging system, for example, energy may be transmitted with the aid of a magnetic field. For this purpose, a transmitter coil housed in a charging station generates an alternating magnetic field which induces an electrical alternating current in a corresponding receiver coil of the battery device. However, an inductive coupling between both devices is required in order for the energy to be effectively delivered from the charging station to the accommodation unit. Thus, the transmitter and the receiver coil, depending on the quality of the inductive coupling, must typically be situated at a relatively small distance of a few millimeters to several centimeters from one another, the inductive coupling capable of being enhanced by a ferromagnetic core in the transmitter and the receiver coil.
In a wireless charging system which operates on the basis of an inductive energy transmission, different problems may arise depending on the configuration. Thus, for example, sufficient detection of a battery pack inserted into the charging station must be ensured, which requires a cyclical “pinging” of the battery device when the charging station is in standby mode. Furthermore, an adequate communication path between the battery pack and the charging station is also necessary in order to be able to determine the point in time when charging or recharging is ended and to communicate the required energy needs. In addition, foreign objects must be clearly and easily detected. Furthermore, a sufficiently robust feedback system for closing the control circuit must also be provided.
Various approaches are already known which provide optical transmission systems for charging systems. The publication DE 29724016 U1, for example, discusses a charging device for a rechargeable battery in which a detection of rechargeable batteries having varying capacitances is implemented with the aid of light barriers. In addition, the charging device includes an IR interface for transmitting information from the rechargeable battery to the charging device.
A charging device for inductively charging a hand-held power tool is discussed in U.S. Pat. No. 5,536,979 A, in which the hand-held power tool communicates the fully charged state of its internal battery cells to the charging device with the aid of a photodiode.
A charging device for charging rechargeable batteries is also discussed in DE 19955985 A1 U1, the charging device including a light barrier for detecting an inserted rechargeable battery.
A rechargeable battery pack having a coding pin for interrupting a light barrier situated in the charging device is also discussed in DE 202009002787 U1.